newbie i did such approach some years ago, im not sure about tuio, but i used OSC messages using an FLASH adobe, interface to send OSC messages into a private server, and then make GS connect to that , and read the stream of data.
Though i just.. stoped that...
You can anyway, use a webcam lib, called touchlib, ( i did used too) and you can search alot of it, from.. nuigroups, and then wrap it to lite-c, and you have direct interpretations of the webcam fingers and inputs...